The present invention relates to fluid-coupling devices of the type including both a fluid working chamber and a fluid reservoir chamber, and especially to providing an improved and more efficient pumping mechanism for removing fluid from the operating chamber.
Although the present invention may be used advantageously in fluid-coupling devices having various configurations and applications, it is especially advantageous in a coupling device of the type used to drive a radiator cooling fan for an internal combustion engine, and will be described in connection therewith.
Fluid-coupling devices (“fan drives”) of the viscous shear type have been popular for many years for driving engine cooling fans, primarily because their use results in substantial saving of engine horsepower. Typical fluid-coupling devices operate in the engaged, relatively higher speed condition only when cooling is needed, and operate in a disengaged, relatively lower speed condition when little or no cooling is required. These devices typically use wipers to control the amount of viscous fluid exiting the working chamber to control the relative engagement of the fan drive at a given input speed. Fan drives controlled by valve metering systems, such as electromagnetic controlled valve systems or bimetal controlled valve systems, achieve a very low disengaged fan speed by removing nearly all the viscous fluid from the fan drive labyrinth, or working chamber, during disengaged operations. This is desirable in that it minimizes parasitic power losses in the vehicle while improving fuel economy.
Conventional wiper systems include separate devices, preferably made of a plastic material, that are positioned between the clutch disk members and the housings. The wiper members are positioned on, or attached to, the inside surface of the housings and operate to pump viscous fluid into a scavenge passageway from the working chamber. The scavenge passageway typically comprises passageways which are machined into the housings.
It is an object of the present invention to provide unique wiper members and scavenge systems for viscous clutches which are improvements over known wiper members and scavenge systems. It also is an object to provide improved viscous clutch mechanisms with such unique wiper members and scavenge systems, and which also may utilize a high-speed reservoir.